This invention relates to heat sealing a thin porous facing sheet onto a non-planar foam surface. It relates particularly to method and apparatus for rapidly heat sealing a thin fibrous facing sheet onto flexible ethylene-containing closed cell foam shells each having a non-planar upper surface.
Heat sealing fibrous plastic sheet materials together by heat softening the mating surfaces is generally known. Such heat sealing operations are usually accomplished on planar surfaces and onto solid materials at relatively slow cycle times of many seconds per cycle. However. rapidly heat sealing plastic fibrous sheets onto ethylene-containing foam materials at short cycle times less than about 5 seconds has presented various difficulties and unreliable sealing results, particularly when heat sealing onto non-planar formed foam surfaces. Such difficulties with rapid heat sealing have now been unexpectedly overcome by the present invention.